Peace talks between the Sudanese government and Darfur's rebel groups could begin next month, according to senior UN officials.

As the UN secretary general, Ban Ki-moon, flew to Khartoum yesterday to check how the newly agreed force of UN and African Union peacekeepers will operate in Sudan's western region, a senior official travelling with him said the political outlook had improved. "If the talks start, we expect the level of violence will go down," he told reporters on Mr Ban's plane.

The UN security council agreed in July almost to triple the number of foreign troops and police in Darfur with the aim of protecting the millions of displaced people. The African Union will continue to supply all the infantry for the 20,000-strong force but other nations will provide transport aircraft, helicopters and logistics, while command will be under joint UN/AU leadership.

Mr Ban's visit, which also includes stops in Chad and Libya, is his first since Sudan's president, Omar al-Bashir, agreed to accept the beefed-up force for Darfur, for which western nations have been pressing for months. A peace agreement negotiated last year collapsed after two of the rebel leaders failed to sign at the last minute. Since then new rivalries have led the groups to split, making the job of UN and AU mediators much harder.

But in Arusha in Tanzania last month the mediators persuaded seven rebel leaders to agree on a common platform for talks with the government, which the official said would open "hopefully next month". "The next stage is that they agree on a negotiating team which, as you understand, is difficult."

Abdul Wahid al-Nur, the founder of the Sudan Liberation Army, which took up arms against the government in 2003 in a bid to end Darfur's marginalisation, boycotted the Arusha talks.

"He is still negative to taking part," the official said. "He wants to have the deployment of UN and AU troops and the full disarmament of militias before the negotiations start." The UN hopes he will change his mind once a venue and date for the talks are fixed.

The government says it is willing to amend last year's failed peace agreement, but rejects wholesale renegotiation.

UN officials say one reason for hope is that - unlike in the last negotiations - the views of displaced people in the camps as well as those of tribal leaders and representatives of women and civil society will be heard.

UN officials fear tensions in Darfur could become explosive if peace is not made soon. Frustration and anger in the camps are growing after four years of misery and homelessness. Deserted villages have started to be taken over by other people who do not own the land, precipitating new violence. UN officials say more people are being killed in tribal clashes - some 600 since January - than in fighting between rebels and government forces or militias.